Strengthened security for cable-TV networks is an indispensable prerequisite to the delivery of e-commerce and electronic administration services via this medium. This report proposes a high-level security system that effectively prevents intrusions by tapping imposture. In this system, encryption is applied on the MAC layer so that the Media Access Control Address is encrypted, the system thus makes it very difficult to collect information on a specific member by tapping.

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This paper describes a sensor system for the detection of foreign objects (FOs) on airport runways. FOs are a major cause of damage to airplanes, and have led to serious accidents. Currently, airport workers visually inspect airport runways for FOs. However, this task is tough and dull; moreover, detection of FOs is difficult, under certain lighting conditions and when the objects are of colors similar to runways and low in height. We propose a sensor system which solves these problems by applying an ultraviolet image sensor and a laser radar for an automatic inspection system that we developed. In the ultraviolet range, objects on the ground are always strongly highlighted by the sky radiation component of the sun's radiation in the daytime. This allows to design a system which is robust in detecting FOs, i.e., it detects the FOs regardless of the direction of the sun, the weather, and the colors and height of the objects. The conditions for the detection of FOs in terms of reflectance are studied, and the validity of the conditions is demonstrated through experiments.

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This paper presents a technique for the digital watermarking of musical sound. It consists of two main steps : the first is the division of the audio-frequency band into several sub-bands and the second is the embedding of a watermark in one of these bands by the spectral spreading method. The proposed scheme produces a watermark that is robust against data compression and ordinary attacks, while retaining high quality for the sound because we randomly select the specific band for the embedding of the watermark among the many sub-bands. For example, our experimental results have shown that the quality of watermarked music is good in about 45dB and that the watermark remains detectable after MPEG1 Audio LayerIII compression and jitter attacks.

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A face-recognition security system for access control is described that is unaffected by the stance of the entrant. Although face recognition has several advantages compared to other biometric techniques, the similarity value used for recognition is affected by the direction that the entrant is facing, the entrant's position relative to the equipment, and the lighting conditions. The proposed system eliminates the second problem by using feedback to stabilize the entrant's position and an efficient method to update the registered data. A six-month evaluation of a prototype system showed that it had a FAR (false acceptance rate) of 0.1% and a FRR (false rejection rate) of 1%. Simulation of one-to-many identification showed that contact-less security is feasible using this system.

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We propose the use of an adaptive discriminant space constructed from facial images of candidate faces to optimally distinguish the faces of certain candidates. Firstly, our method to select the set of candidates uses a hierarchical combination of the four-directional features for face-direction estimation and recognition based on linear discriminant analysis. Next, the exact directions of the faces are estimated from the respective discriminant spaces for face-direction estimation. Finally, our method creates a new discriminant space from the facial images of candidates that were selected on the basis of the results of the procedure for face-direction estimation. This adaptive discriminant space is used in opimally selecting from among the candidates. Experiments showed that our method improved the accuracy in recognition by 1.6% to 99.2% by hierarchical face recognition of 105, 000 images from 150 subjects facing in 35 different directions.

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[in Japanese]

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In hand-drawn illustrations, we often draw pictures that contain lines of varied thickness. In some animations, the thickness of each line which makes up an image changes according to the direction of the view. However, traditional methods of rendering do not capture this effect. We thus propose a view-dependent method of line rendering. That is, after creating the 3D data for an object, a user sets, for each line, thickness information that has a dependence on the view direction. This information is stored in a user-defined reference table that is called the line-rendering information table. A user is thus able to freely set line-rendering thicknesses for the individual objects such that the thickness of each line is controlled according to the direction from which it is viewed.

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Estimation of the scattering of electromagnetic waves by buildings and other obstacles is very important for wireless communications in urban areas. In this paper, the electric fields of the waves, which are transmitted from one side of a building to travel over its rooftop to reach the other side were calculated on the basis of the GTD including slope diffraction for the cases where rooftop obstacles are and are not present. The fields as diffracted by a square obstacle and a conductive plate on a rooftop of a building are also discussed. The numerical results show that most of the diffracted waves that travel along the rooftop surface are slope-diffracted, and that installing a conductive plate of suitable height on the building's rooftop is a fairly effective way of improving the received level of electric field strength.

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[in Japanese]

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In order to increase the receiving power of the Fresnel-zone plate antenna suitable for the reception of signals from multiple Television-Broadcasting satellites, a reflector-type antenna is developed where an additional reflector plate provided 1/4 of a wavelength behind the Fresnel-zone plate with a the dielectric material. Received power and phase for the oblique incident waves are calculated on the basis of traditional ray theory and the antenna's configuration using Kirchhoff's diffraction-integral equation. The correction by the transmission characteristics of the dielectric substrate plate, which also works as a phase shifter, is conducted experimentally. The result was that a good image is received when the angle of incidence is less than 30 degrees and the level of power received at the fabricated multi-beam reflecting antenna is in good agreement with the results of calculation. When combined with a horn receiver, this reflector antenna achieved the high value for aperture efficiency of 22 % for the perfect TV.

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The purpose of this study was to quantify the degree of “Mura”, which is the luminance non-uniformity of an LCD, from the human-factors point of view. A subjective evaluation was carried out to obtain the JND (just-noticeable-difference) and Distinct levels of Mura. Thirty-one kinds of Mura with circle and rectangle shapes were simulated on a TFT/LCD display for evaluation by subjects. The result indicated that both JND and Distinct levels of Mura is influenced most by the area of Mura. The larger the Mura, the more easily it is detected and becomes annoying. The degree to which is annoying Mura was found to be expressed as a function of area and the contrast of the region of Mura. A new unit, “JND” that indicates the degree to which Mura is annoying, had thus been created; 1.0 JND corresponds to the limit for Mura being noticeable and 3.0 JND is the boundary of the Distinct level. The outcome of this study has already been applied in manufacturing processes and this has been effective.

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This paper presents a new interface that gives users the ability to use their body to control their viewpoint direction in virtual environments without loosing sight of the displayed images, despite the use of a limited large screen system. To keep users provided with continuous visual feedback even when users perform a full body rotation, the interface uses a turntable device as a platform on top of which users will stand at its center and which is capable of canceling users' body turning by a smooth and passive rotation in opposite direction of the turn. Turntable rotation is optimized and synchronized with the displayed images so as to maintain a stable visual feedback that do not affect users' perceptual capabilities. The interface is shown to be simple and adaptable to most virtual environments with large display system and can be integrated with other user interface devices such as haptic devices and omni-direction locomotion devices.

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